Abstract:
The digestive physiology of six three-toed sloths (Bradypus tridactylus) fed exclusively on Cecropia palmata foliage was studied. The mass of digesta in the gut was between 17 and 37% of body mass. This was between 133 and 282% of that expected in an animal of this size, based on published allometric equations. The concentration of total short chain fatty acids in the stomach was similar to that in the fermentative regions of other foregut fermenting herbivores but the rate of fermentation measured in vitro was very slow (6–12 mmol.l-1.h-1) and substantially lower than that observed using similar techniques in other small foregut fermenters.

The overall (dose to excretion) mean retention time of particulate and solute digesta markers was about 150 h. Most of this (73%) occurred in the stomach but a substantial proportion (17%) could be attributed to the storage of faeces in the rectum.

The slow rate of passage of digesta through the gut together with the slow rate of fermentation in the stomach is not typical of small foregut fermenting herbivores. However, such a pattern is feasible in Bradypus tridactylus because of the large volume of digesta retained in the gut and the very low metabolic rate of these mammals.

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Unusual Habits

Sloths are famous for their unusual and bizarre bathroom habits – they will only relieve themselves once a week and can lose up to a third of their body weight in one sitting! Furthermore, they will only do it on the ground. This weird weekly routine remains one of the biggest mysteries surrounding sloth behaviour. The likely explanation is that it’s all about communication and reproduction.